Hi Cookies,
Welcome to the forum. When you say things have deteriorated do you mean they’ve escalated? It’s very common for abusers to threaten suicide if they feel us pulling away.
I don’t want to alarm you but you need a safe exit plan. Don’t discuss your plans with him. Get legal advice and open up to your GP, friends or family. You’ll need a strong support network.
If he threatens suicide call the police – they have a duty to respond and will involve mental health professionals if necessary.